Statistical models

Abstract

Research begins with theories and hypotheses. For instance, it may have been noted that many people experiencing a stroke tend to have high blood pressure. You get the idea that medication aimed at lowering blood pressure may therefore also reduce the risk of a stroke. However plausible this sounds, it requires an investigation (a study) to confirm or reject this suspicion. For instance, the apparent connection between high blood pressure and stroke may be simply due to the fact that people experience stroke at an older age where blood pressure is also increased and hence that lowering of blood pressure has no effect on the risk of a stroke because it does not change the age of the individual.